Being able to implement all the things human are good at, however, should be able to get us everything that we could do, because anything we could create, it could create too.

AGI that is as smart as say a rat would easily qualify as AGI even without language skills.

Indeed, but while a full language-using AI is ways a way at least, using language is one thing that's at sort-of describable/comprehensible as a goal. A rat is a lot more robust than any human made robot but how? Overall, I keep hearing these "there's intelligence that's totally unlike what we conceive" argument but it seems like computer programs as they exist now either do what a human could do rationally and more quickly (a conventional program) or heuristic duplicate human surface behavior (neural nets). You could sort-of argue for more but it's a bit tenuous. Human behavior is very flexible already (that's the point, right). And assuming AI is hard to create, creating something who properties we to-some-extent understand is more like than creating the wild unknown AI.

Also, "Getting to rat level" might not be the useful path to AGI. If we simply created a rat like thing, we might win the prize of "real AGI" but it would be far less useful than something we could tell what to do the way we tell humans what to do.