A simple question:
Since ET says that monkeys and apes and Humans descended from a common ancestor,
did the CA have an opposable thumb for a big toe and the Humans devolved it;
or did he NOT have an opposable thumb for a big toe and the monkeys and apes EVOLVED it?
Yes it did.
and the Humans devolved it;
There is not such thing as "devolving". Change across generations in any direction is still evolution, just as driving your car in any direction is still traveling. You are not "detraveling" as you return from your destination, or drive to the store in reverse gear.
You seem to be under the common but quite incorrect misconception that evolution necessarily requires some sort of "upward" or "more progressive" result. It does not. Losing a feature is just as much evolution as gaining one, as in the blind cave fish who have lost functioning eyes through countless generations of living in a dark environment.
Furthermore, the "loss" of the opposable toe is overstated, and in any case hardly a decline in fitness -- for our very useful upright gait, our "flat" toe configuration is *more* functional than a chimplike opposable toe, for it makes us able to better walk and run bipedally, which among other things frees our hands for full-time specialization. On the whole, it's a big improvement.
Finally, people who do not have the use of their arms often gain, through practice, an amazing amount of "opposable toe-ness" through practice, and are able to deftly pick up and manipulate things using their feet as "hands" and their toes as "fingers", including being able to paint portraits, etc. There is more opposability left in our toes than most of us ever make use of. For example, read up on Christie Brown, the real-life subject of the film, "My Left Foot".
or did he NOT have an opposable thumb for a big toe and the monkeys and apes EVOLVED it?
No, the fossil evidence is clear.