@Quehoniaomath,
Not all orders of organisms share large amounts of genes between them. Only closely related forms (like apes and humans) or fish and amphibians are closely aligned.
The distances between the genomes of entire orders shows that some are derived and others are not after a deep time common ancestor.
we can trace the fossil record nd find evolved forms first appearances at a time that generally agrees with the occurrence of new genes in the evolved forms.
Genes can be used as a timeclock, a test of similarity (and probable evolution of similar species), AND a test of dissimilarity for species not apparently related.
Like the genomes of Hominids , hominims and new world apes share common genes that predate the final split up of Centarl America from Africa. Then new world apes have their own spcial genomes that differ abundantly from old world apes and Hominims.
genomes can be like etymylogical analyses of words that "travel" from civilization to civilization. (That's a Fairbanks observation , not mine)