As for the comparisons between the different eras, I've always found this video illuminating. It's not about football but it uses an individual sport with a clearer and easier to agree upon goal to compare how much better sportsmen are really. And the real answer is — not by that much.
The biggest difference between the 60's/70's and now would be not the level of top players but a level of average footballer — this is where all the modern bonuses really start to influence the outcome (better training, fitness & tactics). But if you think that pressing is something new, watch Lobanovsky's teams from the 1970's & 1980's that ran the opposition into the ground. If you think that older players won't be able to match modern ones physically, look at many examples of players that started out in the 90's/early 00's and seamlessly transitioned into modern era — look how easy Giggs, teenage prodigy from the early 1990's, found football in 2010's; Pirlo, a player who never was known for his athleticism, completely and utterly dominating the 2010's Serie A aged 31 to 36.
Are you saying that Lukaku, for all the meme value a very successful modern footballer with outstanding international record and multiple 20+ goal club seasons, who only found out that he can lose weight by eating chicken & salad after moving to Inter at the age of 26, can play today but Pelé would struggle with the physicality?
P.S.
To be clear — a top club of today will outplay Real Madrid of the 1950's with a relative ease, I'd imagine. And a midtable Premier League club will completely dominate a midtable club from any top league from the 1950's-70's (I'm excluding 1980's & 1990's due to the insane strength of Serie A and it's foreign players rule). But when we compare individuals, crème de la crème, there really isn't that much of a difference, especially if you give them time to acclimatize.