Was there really any Proto-Greek?

The common thinking abour Greek and also other IE branches, is that
each branch had their proto-language descended from common IE, and
that these proto-languages branched further into the historic
attested dialects.

However, the greek language is attested very far back in time,
espesially the greek of Kreta.

The strange ting is this: Even the most early attested Greek shows
the main dialectical differentiation that is seen in later times.

This means that any such thing as Proto-Greek has to been placed
very far back in time, and very near common IE.

Perhaps Proto-Greek never existed. Perhaps the Greek language
evolved in a geographically confined area from several IE dialects
or branches that mutually influenced each other.

Perhaps the Greek dialects even were independent IE branches before
the tribes speaking them entered the Greek Sone.

Does anyone have thoughts or additional comments about this question.