Yeah, it's all a matter of luck that distinguishes a Messi from a Maradona.
Nope. It's about leading by example with world class performances and inspiring others to maximise their efforts. Cruyff almost did it with Holland in 1974 but didn't, and with a great Dutch team; Messi almost did it with a very good Argentina team 2014; Pele did it with possibly the greatest team of all time in Mexico 1970; Zidane did it with a very good French team in 1998...Maradona did it with a reasonable Argentine team in Mexico 1986.
In regards to the competence of your teammates yes it’s a huge slice of luck. Put Higuain in the Maradona team, he doesn’t score, no trophy. Put Valdano in the Messi team, he scores, trophy.
Messi’s biggest achievement with Argentina was single handedly (and it was literally single handedly) getting the worst Argie team in history to last year’s World Cup by scoring a hat-trick in a 3-1 win at altitude in Equador, a place they hadn’t won at since 2001.
When Maradona was playing, Argentina were winning youth world championships galore. There was a conveyor belt of class Argie players coming through. In Messi’s entire era, the worst in Argie history, they haven’t won a youth title since 2007. No quality midfielders in the team is often talked about, but they haven’t produced a solid defender in that time either (Ayala was the last). Marcos Rojo would have never smelt the Argie squad in Maradona’s era nevermind start in central defence. This is why they get hammered on a regular basis (conceding 4 vs Germany in being eliminated in 2010, a joke of an Argie team with the managerial clown Maradona in charge, conceding 4 vs France in 2018 in being eliminated).
Tim Vickery (BBC’s South American pundit, and the best in the game imo) said the only time Messi was in a good Argie team was in 2006, when he was only just starting to get into the team at 19. Argentina are big in name only, their team has been [Poor language removed] for over a decade.
You're correct that you can only really compare players from the same era. So lets do that. In the 80s, Maradona wasn't head and shoulders above his peers, with Platini, Zico, Matthaus all very much producing similar performances for their clubs and countries. Even Hagi or Laudrup could be spoken of in similar terms.
Now look at the modern era of Messi and ask yourself who does anything similar to him in even short bursts, let alone for the length of time he's done it? The field whittles down to Ronaldo and Neymar, and neither really do it.
Your right in terms of names being mentioned before him, and the one man who agrees is Maradona himself. He spoke of going into Mexico ‘86 he wasn’t talked about in the same way Zico or Platini were. Think it’s in the Football’s Greatest series where he stated he was only the fifth/sixth name, nothing like the Messi talk going into tournaments.
Maradona did go on to prove he was a class above his contemporaries. The issue comes when he is compared to Messi when the two played in entirely different eras, and one in a much stronger Argie team.