It seems to me that the inter-related web of complexity-of-design, in the so-called “horizontal gene transfer” is most plausibly accounted for by commonalities in a Designer, than by some unaccounted-for cross-special transfer.
Just as Ferraris and Fiats share certain core parts (circuits, lightbulbs, steel, copper, rubber, etc) while being completely different animals, as it were, and the most logical explanation—and what we know from history—is commonality of the designer (or designers, in this case). So too it makes sense that from the molecular level, into DNA/RNA, on up to the shape of an eye, or the hands of man and monkeys, the commonality was originally found in the mind of God—not some imagined utterly-hypothetical inter-species transfer.
Thank God the tree is falling...may the web not ensnare us also!
(It is interesting how the models for science follow the prevailing philosophies of the day, eh? Modernism was all about universal paradigms (like that of a Tree), while post-modernism is all about a Web of related-ness, and skepticism toward any universals).
But God created man in his image. Do animals also share this commonality? Strange that God thought so little of man as to use his old design and not come up with perfect ones.