Biological anthropologist here. To add on to what others have said, another idea is that we're meant to be energetically efficient. We know from lab experiments that bipeds burn about half the calories that same sized quadrupeds do when walking. Standing up meant that we individually need less food to survive and could support larger populations on the same land than a quadruped could.

There's also the Provisioning Hypothesis, which relies on the idea that our ancestors were monogamous and that bipedalism freed up the hands in order to gather food more efficiently. Prehistoric monogamy seems like a big jump, but when you compare us to the other primates, the male/female size differences are pretty mild. They're more like what you see in monogamous primates like gibbons and less like ones that have "harem" social structures like gorillas, where the males are much, much larger than the females. (Honestly, I still think it's a bit of a leap though.) Monogamy meant that males can be reasonably sure that their mate's offspring are also theirs, so it makes sense for the males to help supply the females and children with food from a reproductive success viewpoint. The extra help feeding the offspring would free the females up for having pregnancies that were a little closer together, and even a slight increase in reproductive rates can lead to outcompeting other groups without that adaptation.

My biggest complaint about the AAH is that the archaeological evidence says that humans seemed to take a very long time to figure out that seafood was delicious. We don't have ample evidence of humans or hominins exploiting aquatic resources until the past 100,000 years or so, at which point we were anatomically the same as we are today.