A great deal of what is believed to have happened this long ago is based on accounts written centuries later and/or archaeological finds that are open to interpretation. If Homer did exist, it shouldn't surprise us that there would be no evidence of it. If Homer didn't exist, it shouldn't surprise us that for a couple thousand years most people said he did.
While any sort of evidence of the existence (or non-existence) of Homer is scant and speculative, there is a good reason why someone from Ionia in Asia Minor some number of centuries before the peak of classical Athens would write from the Greek perspective.
After the traditional (and by traditional I mean the Ancient Greek tradition) date of the Trojan War, Ionian Greeks colonized the area where Troy supposedly was. From Wikipedia:
According to Greek tradition, the cities of Ionia were founded by
colonists from the other side of the Aegean. Their settlement was
connected with the legendary history of the Ionic people in Attica,
which asserts that the colonists were led by Neleus and Androclus,
sons of Codrus, the last king of Athens. In accordance with this view
the "Ionic migration", as it was called by later chronologers, was
dated by them one hundred and forty years after the Trojan War, or
sixty years after the return of the Heracleidae into the Peloponnese.
People think the author of the Illiad may be from there because he accurately describes a handful of distinct climate patterns, geographical features, and uses their dialect.