There's no slam dunk argument as I've said- but one way to look at it;
natural selection itself goes without saying, your aliens could excavate our auto junk yards, plot the various species on an almost identical tree showing the natural selection of incremental improvements over time. complete with some large gaps, mass extinctions, varying traits according to local environment , sudden explosions of innovation, a few regressions, redundant features, but a general trend towards greater complexity, functionality, and diversity, yes?
We know of course that the changes in design to be selected from here were not random, they were overwhelmingly beneficial by design with a smattering of detrimental ones. totally opposite from evolution as you just said yes? Yet this process leads to an almost identical tree of life as we see in the fossil record
Random mutation is the exact mirror of this, random mutations to be selected from are overwhelmingly detrimental with a smattering of improvements as we agree.
What would it look like if the auto co. decided to save on R+D and simply make entirely random changes and let the best be selected.
Natural selection still operates, but since there are far more detrimental changes, the best is now in practice the least damaged. The car with the broken passenger seat warmer is selected over the one with the broken engine. And so on as we lose the radio, windscreen, roof, brakes, but can at least still move- while regressing all the way back to the simplest, homogenous, basic design that answers it's simplest fitness function- mobility- the first basic bicycle at the base of the tree.
For life, the fitness function is replication, no more, no less- that would be the result (at best) of random mutation and natural selection left to it's own devices.
must run will respond later- I appreciate the thoughtful conversation