As with all historical questions, the answer is complicated. To put it simply, relations started off promisingly but quickly degenerated into terrible mistreatment of the Indigenous population. Of course, there were exemptions and outliers and some people had very good relationships with Aboriginals. I’ll look at some primary sources from the first year of contact (1788) which you might be interested in.

This is a letter which Governor Phillip wrote back to England on the 15th of May, about 3 ½ months after the arrival of the First Fleet. It shows that he originally had good intentions- or at least, not bad ones- towards the Indigenous population.

it was my determination from my first landing that nothing less than the most absolute necessity should ever make me fire upon them…

When I first landed in Botany Bay the natives appeared on the beach, and were easily persuaded to receive what was offered them, and, tho’ they came armed, very readily returned the confidence I placed in them, by going to them alone and unarmed, most of them laying down their spears when desired; and while the ships remained in Botany Bay no dispute happened between our people and the natives.

The relations between the Aboriginals and Fleeters in the beginning, while tentative, were generally positive.

When I first went in the boats to Port Jackson the natives appeared armed near the place at which we landed, and were very vociferous, but, like the others, easily persuaded to accept what was offered them, and I persuaded one man, who appeared to be the chief or master of the family, to go with me… He then went on with me to examine what was boiling in the pot, and exprest [sic] his admiration in a manner that made me believe he intended to profit from what he saw, and which I made him understand he might very easily by the help of some oyster-shells.

The same people afterwards joined us where we dined; they were all armed with lances, two with shields and swords — the latter made of wood, the gripe small, and I thought less formidable than a good stick. As their curiosity made them very troublesome when we were preparing our dinner, I made a circle round us. There was little difficulty in making them understand that they were not to come within it, and they then sat down very quiet.

In Broken Bay several women came down to the beach with the men where we landed, one of which, a young woman, was very talkative and remarkably cheerful. They all readily assisted us in making a fire, and behaved in the most friendly manner.

Etc. Etc.

This letter, however, also shows instances of cultural misunderstanding and mistreatment.

When we returned, two days afterwards, to the spot where the old man had been so friendly he met us with a dance and a song of joy. His son was with him. A hatchet and several presents were made them, and as I intended to return to Port Jackson the next day every possible means were taken to secure his friendship; but when it was dark he stole a spade, and was caught in the fact. I thought it necessary to show that I was displeased with him, and therefore, when he came to me, pushed him away, and gave him two or three slight slaps on the shoulder with the open hand, at the same time pointing to the spade. This destroyed our friendship in a moment, and seizing a spear he came close up to me, poised it, and appeared determined to strike; but… after a few moments he dropped his spear and left us…. He returned the next morning with several others, and seemed desirous of being taken notice of; but he was neglected, whilst hatchets and several other articles were given to the others.

There is also an account by David Collins which gives much the same overview. Start from “it was natural to suppose” on page 51 of this book. I’ll pull out a passage which I think is particularly pertinent:

To such circumstances as these must be attributed the termination of that good understanding which had hitherto subsisted between us and them, and which Governor Phillip laboured to improve whenever he had an opportunity. But it might have been foreseen that this would unavoidably happen: the convicts were every where straggling about, collecting animals and gum to sell to the people of the transports, who at the same time were procuring spears, shields, swords, fishinglines, and other articles from the natives, to carry to Europe; the loss of which must have been attended with many inconveniences to the owners, as it was soon evident that they were the only means whereby they obtained or could procure their daily subsistence; and although some of these people had been punished for purchasing articles of the convicts, the practice was carried on secretly, and attended with all the bad effects which were to be expected from it.

We also had the mortification to learn, that M. De la Perouse had been compelled to fire upon the natives at Botany Bay, where they frequently annoyed his people who were employed on shore. This circumstance materially affected us, as those who had rendered this violence necessary could not discriminate between us and them. We were however perfectly convinced that nothing short of the greatest necessity could have induced M. De la Perouse to take such a step, as we heard him declare, that it was among the particular instructions that he received from his sovereign, to endeavour by every possible means to acquire and cultivate the friendship of the natives of such places as he might discover or visit; and to avoid exercising any act of hostility upon them.

Watkin Tench also gives an account:

With the natives we were very little more acquainted than on our arrival in the country. Our intercourse with them was neither frequent or cordial. They seemed studiously to avoid us, either from fear, jealousy, or hatred. When they met with unarmed stragglers, they sometimes killed, and sometimes wounded them. I confess that, in common with many others, I was inclined to attribute this conduct, to a spirit of malignant levity. But a farther acquaintance with them, founded on several instances of their humanity and generosity, which shall be noticed in their proper places, has entirely reversed my opinion; and led me to conclude, that the unprovoked outrages committed upon them, by unprincipled individuals among us, caused the evils we had experienced. To prevent them from being plundered of their fishing-tackle and weapons of war, a proclamation was issued, forbidding their sale among us; but it was not attended with the good effect which was hoped for from it.

This (somewhat) interactive SBS documentary is an amazing resource for getting an overview of Aboriginal history generally. I highly recommend you spend some time going through this.

Wouldn't the first people to land in Australia have been the Aboriginals? By nature of them being first, there wouldn't have been any natives. Unless you're referring to kangaroos.