These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
The original work was also somewhat left wing oriented, having in mind the protagonists are a small army (or guerrilla), fighting a bigger enemy army which is obeying the villain against it's will. Even if it's nowhere in the first part, Oesterheld's motto for the book was "el único héroe válido es el héroe en grupo, nunca el héroe individual, el héroe solo" ("the only true hero is the group-hero, never the individual hero, the lone hero)"''. All and all, the First part was a LOT more subtle than the second part (if you can call the it subtle at all).
I got a major humanist feel from the first one, would barely say it conveyed any left wing message (Not to imply humanist and leftist messages are mutually exclusive).
Seconded. It is a common mistake to read his fifties' works through his seventies-late sixties political involvement. It is however true that, in any case, it was that humanism which got him more politically involved, it's all part of a slow process that is, by the way, a very useful example of what happened to many humanist and mildly leftist intellectuals in Argentina after several years of corruption, disillusionment and dictatorship.
They Changed It, Now It Sucks: While the original series is widely regarded as Made Of Awesome and even taught in schools in Argentina, the Second Part in comparison is considered inferior by many hardcore fans. The same thing is true for the 2000's in-universe sequels made by Solano López and Pablo Maiztegui, though it was a serious product and sold fairly well, itself a miracle given the Argentine economics.