I know that by the middle of the following century there was all out conflict, but what was life like in the decades before this point? Did the average person have much to fear from the VOC/Dutch, or were their actions more directed toward political entities?
edit: I'm an idiot and actually meant the 1600s, not the 15th century. Numbers are hard.
The VOC had no activities and no impact anywhere at all at the end of the 15th or even 16th centuries, mainly because it didn't exist until 1602. But I get the gist of your question, so here goes: the turbulent relationship between the VOC and Gowa/Makassar, the empire ruling all South Sulawesi, up to 1656, and its effect on everyday life. The VOC had no relations with any other S. Sulawesi state until 1660, so I will discuss only Gowa.
Oh, and a nice Dutch poem to start us off:
Gentlemen, there follows now something of the malevolent Makassar,
In the island of Sulawesi; in the entire East Indies there was
No more villainous race than this, rascally, perjured, malign,
murderous, malignant, savage, perfidious.
[...]
In short, they were scoundrels
spawned by Lucifer, the most desperate ruffians...
But war and hatred were not the only facets of the VOC-Gowa relationship.
In 1607, the representatives of the five-year-old Dutch East India Company (VOC) received an invitation from the king of Gowa, the dominant state of South Sulawesi, to trade in his country. Little did either sides understand the transformative century of immense change that both Europe and South Sulawesi had just undergone.
In the first decade of the 16th century the peninsula of South Sulawesi was fragmented into a number of small complex chiefdoms, of which the most prominent included Gowa, Bone, Wajoq, and Luwuq.^1 This geopolitical situation would begin to shift in the early 16th century, when Gowa emerged as the peninsula's first state. It began with Tumapaqrisiq Kallonna (r. c. 1511-1546) of Gowa, who subjugated his immediate neighbors, created the first bureaucratic posts, and generally set the stage for expansion across the entire peninsula. This rapid expansion was accomplished by his son Tunipalangga (r. c. 1545-1565), who conquered the entire peninsula save Gowa's archrival Bone, vastly expanded the bureaucracy, and - perhaps most importantly - oversaw the establishment of the first permanent Malay community in Gowa's port capital of Makassar.^2
With the establishment of the Malays^3 - by far the most important merchant diaspora in 16th-century Southeast Asia - in Makassar, trade expanded greatly. Tunipalangga had conquered the main competitors of Makassar in his great conquests and allowed Makassar to emerge as the natural entrepot for produces from across eastern Indonesia, especially the fine spices from Maluku. Gowa's expanding empire itself provided a source of commercial wealth, for instance by selling tribute from its newly acquired vassals.^4
By 1600, after a brief interlude in the early 1690s when a tyrant discouraged trade, Makassar had emerged as the preeminent commercial center of all of eastern Indonesia. Just one year after the VOC was founded, the Dutch reported that their Portuguese enemies were annually sailing from Melaka, their base of power in Southeast Asia, to Makassar to load their ships with spices. In 1605 Malay merchants may have suggested the tumabicara-butta (chancellor/prime minister) of Gowa to convert to Islam, who was soon followed by the young king himself. But Muslim or not, Gowa-Talloq^5 (see note 5 for why I'm calling it Gowa-Talloq now) committed itself to a general policy of free trade, at least in the port of Makassar itself.
The Dutch, of course, wanted to join the game. After an invitation from the king of Gowa the Dutch arrived, hoping to convince Gowa-Talloq to surrender its support for Portuguese Melaka... and were very disappointed to learn that the king believed that
My country stands open to all nations, and what I have is for you people [the Dutch] as well as for the Portuguese.
The VOC sought to establish monopolies on key Southeast Asian produces, especially the fine spices of clove, nutmeg, and mace. They could then control prices and raise artificial profits. The continual of Makassar's trade of spices made such a monopoly impossible. Furthermore, Makassar was providing safe haven for enemies and competitors of the Dutch, such as the English (who established a factory in 1613) and the Spaniards (whose agent first arrived in 1615). Already, by 1614, a Dutch commissioner was recommending that the Company attack Makassar shipping in Maluku, the Spice Islands.
In 1615 the Dutch informed Gowa-Talloq that there was now a Dutch monopoly in Maluku and that Makassar ships should refrain from heading there. The king of Gowa's response was simple:
God made the land and the sea; the land he divided among men and the sea he gave in common. It has never been heard that anyone should be forbidden to sail the seas. If you seek to do that, you will take the bread from the mouths of the people. I am a poor King.^6
As for daily life, not much would have changed - just a new group of merchants on the scene, just like the Malays had arrived in the late 1400s and the Portuguese in the early 1500s. The Dutch had not yet established a definitive monopoly on any of the fine spices and hadn't even acquired Batavia.
War began a few months later, when the VOC factor Abraham Sterck got frustrated about the king of Gowa not paying some debts. Claiming the government in Makassar had failed to protect him from the insults of the Spaniards (with whom the Dutch were still at war), Sterck left abruptly with a number of Gowa-Talloq nobles. The nobles resisted and seven were killed, including a nephew of Gowa's king. The harbormaster of Makassar and another royal relative was taken as prisoner of the Dutch. This incident infuriated Gowa-Talloq and almost resulted in the ousting of the English as well, since the English factor had for some reason left with the Dutch. The English managed to stay, but the Dutch did not.
And... I hate to end on a cliffhanger, but I'm not even half done, but I've hit 9988 characters and it's 22:52 here. I'll finish tomorrow, promise.
There is an emerging consensus that there were no genuine states in South Sulawesi in 1500, insofar as it matters to distinguish an archaic state from a complex chiefdom. This is best presented in Tale of Two Kingdoms: The Historical Archaeology of Gowa and Tallok, archaeologist David Bulbeck's thesis, which most archaeologists cite. But on chiefdom vs state in South Sulawesi, also see The Lands West of the Lakes: A History of the Ajattappareng Kingdoms of South Sulawesi, 1200 to 1600 CE by Stephen C. Druce and Land of Iron: The historical archaeology of Luwu and the Cenrana valley by Bulbeck and Ian Caldwell, both by archaeologists.
^2 On 16th-century Gowa, a lot of sources. If you want the pure, undistilled facts, I refer you to William Cumming's 2007 translation A Chain of Kings: The Makassarese Chronicles of Gowa and Talloq. But check the notes, because Cumming's translation often differs from other historians'. The simplest narrative secondary source, if a bit dated on the archaeological aspect, is the first chapter of Leonard Andaya's The Heritage of Arung Palakka: A History of South Sulawesi in the Seventeenth Century. A lot of articles mention the 16th-century as well, but few exclusively so.
^3 Itself a catch-all term for merchants from the Western Archipelago generally. Anakoda Borang, the first leader of the community that would later be known as the Makassar Malays, said that anyone who wears a sarong - from a Cham in central Vietnam to a Minangkabau from southwestern Sumatra - is Malay. See Heather Sutherland's chapter "The Makassar Malays" in Contesting Malayness: Malay Identity Across Boundaries. Also note that in Makassar usage, the word 'Java' (jawa) just means anyone who comes from the Central or Western Archipelago, including Malays. So the Makassar didn't really differentiate different groups of foreign Southeast Asians in language.
^4 For the rise of Makassar and its trading networks in the late 1500s, there is good information in Leonard Andaya's chapters "Applying the Seas Perspective to Indonesia" in Early Modern Southeast Asia, 1350-1800 and "Eastern Indonesia: A Study of the Intersection of Global, Regional, and Local Networks in the 'Extended' Indian Ocean" in Reinterpreting Indian Ocean Worlds: Essays in Honour of Kirti N. Chaudhuri.
^5 Talloq was a small maritime kingdom that was founded during a succession dispute in Gowa around 1500. It was conquered by Tumapaqrisiq Kallonna and brought into Gowa's fold. But when King Tunipasuluq, who apparently did so many horrible things that the Gowa Chronicle applies damnatio memoriae on him and refuses to mention what he actually did, was kicked out, it was Karaeng Matoaya - king of Talloq - who was at the head. As tumabicara-butta and regent for the new boy king of Gowa, Karaeng Matoaya became the most influential man in South Sulawesi. Archaeologist David Bulbeck's research shows that during the reign of Kng. Matoaya, Matoaya's kingdom Talloq was actually considered more powerful than Gowa, at least as far as we can infer from dynastic marriage trends. During Matoaya's reign Talloq also controlled the port of Makassar. See Bulbeck's chapter "The Politics of Marriage and the Marriage of Polities in Gowa, South Sulawesi, During the 16th and 17th Centuries" in Origins, Ancestry and Alliance: Explorations in Austronesian Ethnography. So I refer to the kingdom as Gowa-Talloq to better reflect this change in the latter's status.
^6 Primarily from Anthony Reid's narrative account "A Greet Seventeenth Century Indonesian Family: Matoaya and Pattingalloang of Makasar," one of few English-language narrative sources on the relations between the VOC and Gowa-Talloq.