Maradona is given the nod because he played in Spain and Italy, in addition to Argentina, and dominated a World Cup with a much weaker team.
And I don't see the competitiveness of leagues/or time holding up as an argument.
Pelé dominated his competition for a long time, he won national and continental championships multiple times as well as being the star in two world cups, one of them at the age of 17, his numbers are better as well.
Maradona in the meantime spent a solid amount of time in both Europe and South America and wasn't continental champion, so relatively speaking, he wasn't as dominant in his time as Pelé was during his own.
And if you argue that competitiveness is ever increasing, you have Messi and Cristiano Ronaldo with much better numbers and a decade-long dominance, I would argue even Zidane, Romario and Ronaldo above him in terms of results.
Maradona comes from a time when governments were highlighting football for need of national unity. Pelé was used for media in the same way.
He's definitely one of the greatest when it comes to how symbolic he is to the game, he represents Argentina's rise to the top of the football world, which has followed as Argentina has consistently put great players since, but I have high reservations as to calling him the best of all time.
You are probably right about the other players that you mentioned as well, and given some distance from their remarkable achievements we will absolutely see them in even higher regard than we already do.
That said, "Pelé: Birth of a Legend" is just a terrible movie... but I am trying not to hold that against him.
Maradona is certainly in the conversation for greatest player of all time, but it's a bit weird to suggest that it's a universal opinion.
In any case, Garrincha was better than either.