The answer to your question depends on what you mean by "the oldest gods."
If, by "the oldest gods," you mean the oldest deities humans have ever worshipped, then I am afraid your question cannot be answered, because historians and religious studies scholars really have no idea who or what the oldest deities humans have ever worshipped were. There is simply no surviving evidence that we could use to answer such a question and the various answers that have been proposed all lack empirical evidence to support them.
Jews, Christians, and Muslims have, of course, long believed that their God is the original God of all humanity and therefore the God whom humans have worshipped the longest. This view, however, is not substantiated by any kind of historical evidence and, since the nineteenth century, critical scholars of religion have generally discarded it.
The Victorian English anthropologist Edward Burnett Tylor (lived 1832 – 1917) proposed an influential cultural evolutionist model for the origins of religion in his book Primitive Culture, originally published in 1871. In this book, he argued that human societies have gradually progressed from the simplest and most primitive form to more complex and civilized forms. He therefore saw the history of religion as a progression of gradually increasing complexity and civilization.
In this model, Tylor posited that the earliest religion of humanity was something he calls "animism," which he defined as "the general doctrine of souls and other spiritual beings in general." He believed that "primitive" cultures around the world still practice animism, while more advanced humans have progressed from animism to polytheism, from polytheism to monotheism, and will eventually progress to reject religion altogether and embrace enlightened scientific rationality.
Modern religious studies scholars generally reject Tylor's idea that there was a single primitive religion of all humanity as simplistic and his idea that this religion was "animism" as an unfounded one rooted in his own colonialist prejudice against Indigenous peoples and their religious traditions. Nonetheless, his idea continues to have influence with the general public and you can still easily find misleading charts online that purport to show the "family tree" of all religions leading back to primitive "animism."
Thus, despite much speculation on the topic, no one really knows what the first deities ever were. If, however, by "the oldest gods," you mean the oldest deities that scholars know of, that question is still complicated, but it is at least answerable.
The oldest deities whose names are directly historically attested are the deities who are mentioned in Sumerian proto-cuneiform tablets dating to the Late Uruk Period (lasted c. 3500 – c. 3100 BCE), such as An (the sky god and ruler of all the other deities), Inanna (a goddess associated with war, sex, love, retribution, and political power), Utu (the sun god who was also seen as an enforcer of justice and moral order), Iškur (a storm god), and Nanna (the moon god).
Scholars also know about the worship of some other extremely ancient deities whose names are not directly attested, such as those worshipped by the original speakers of the Proto-Indo-European language, who, according to the currently most widely accepted hypothesis, lived in the steppes north of the Black Sea in what is now Ukraine and southern Russia from around 4500 BCE to around 2500 BCE. The language these people spoke and the deities they worshipped are not directly attested, but, by comparing the deities worshipped in later ancient cultures that spoke languages derived from Proto-Indo-European, scholars can reconstruct some of the deities the original speakers of Proto-Indo-European worshipped.
You can find in-depth discussion of the various Proto-Indo-European deities scholars over the years have proposed in works such as the book The Oxford Introduction to Proto-Indo-European and the Proto-Indo-European World by J. P. Mallory and D. Q. Adams (published by Oxford University Press in 2006) in the chapters "Religion" (pages 408–414) and "Comparative Mythology" (pages 423–441) and the book Indo-European Poetry and Myth by M. L. West (published by Oxford University Press in 2007).
The most solidly reconstructed Proto-Indo-European deity is *Dyḗus Ph₂tḗr, whose name means "Sky Father" and seems to have been regarded as the god of the daylit skies. His name is the source for the names of the Luwian god Tātis Tiwaz ("Papa Tiwaz"), the Palaic god Tiyaz Pāpaz ("Papa Tiyaz"), the Vedic god Dyáuṣ Pitṛ́, the Phrygian god Tiy-, the Greek god Zeús Patḗr ("Father Zeus"), the Roman god Iūpiter ("Jupiter"), the Oscan god Dípatír, the Illyrian god Deipáturos, the Norse god Týr, the Old English god Tīw, the Lithuanian god Diēvas, and the Latvian god Dievs.
Another reasonably solidly reconstructed Proto-Indo-European deity is *H₂éusōs, the goddess of the dawn, whose name means "Dawn." Her name is generally thought to be the source for the names of the Vedic goddess Uṣás, the Greek goddess Ēṓs, the Roman goddess Aurōra, the Old English goddess Ēostre, the Lithuanian goddess Aušrinė, and the Latvian goddess Auseklis.
There are also deities in other cultures who are first attested in the historical period, but who modern scholars speculate may have had direct precursors in prehistoric eras. For instance, archaeologists discovered (amid an array of iconographically similar depictions) a baked-clay statuette of a corpulent nude female figure seated on a throne with hand rests carved to look like the heads of two large felines with her legs spread apart, apparently in the act of giving birth, at the site of Çatalhöyük in Asia Minor. This statuette is dated to the sixth millennium BCE and is known as the "Seated Woman of Çatalhöyük."
Some aspects of the statuette (such as the figure being a "mother," her being depicted seated on a throne, and her being associated with large felines) recall the later goddess Matar Kubileya, whose cult is well attested in the region of Phrygia in northwest Asia Minor from the Early Iron Age (lasted c. 1200 – c. 750 BCE) onward and who was often represented seated on a throne with at least one lion by her side.
The cult of Matar Kubileya was introduced to the Greek world by at least the sixth century BCE and the goddess became known among the Greeks by names such as Κυβέλη (Kybélē), Μήτηρ Μεγάλη (“Great Mother”), and Μήτηρ Θεῶν (“Mother of Deities”). The Romans later officially adopted her into their pantheon in 205 BCE as Cybelē or Magna Māter (“Great Mother”).
James Mellaart, the original excavator of Çatalhöyük, and many scholars of ancient religion after him, including the very eminent German scholar of ancient Greek religion Walter Burkert, were not at all hesitant to claim that the "Seated Woman of Çatalhöyük" statuette represents a Neolithic Anatolian mother goddess who is the direct ancestor of Kybele.
More recent scholars, such as Lynn E. Roller in her book In Search of God the Mother: The Cult of Anatolian Cybele (published in 1999 by the University of California Press) on pages 27–39, have evinced greater skepticism toward the idea that the statuette really represents a direct precursor to Kybele, but still hold that the statuette is an important part of the background for Kybele's later development.
