You focus on the magic 98% similarity between chimps and humans. And I know why - because this is not the most compelling aspect of the DNA similarity evidence.
Three other lines of evidence are far more interesting IMO:
Human chromosome 2 - appears to consist of the cobbling together of two ape ones.
Chromosome fusion.
The same retrivirus DNA insertions are found in human and ape genomes. Bear in mind that these are non-functional DNA sequences that are the result of ancient viral infection
Just a moment...
Finally, we share with the apes a faulty Vitamin C synthesis gene
29+ Evidences for Macroevolution: Part 2.
I can imagine that for His own reasons God would not give us the ability to synthesise vitamin C, but why on earth do so by giving us the gene and nobbling it? And, more to the point, why give the same nobbled gene to the great apes? Anyone would think He's trying to make us think we evolved.
Your explanation of these from a "common designer" viewpoint is eagerly awaited.