Morphy games are both highly instructive and highly entertaining. The ideas he helped to develop were so far ahead of his time. He showed how powerful it can be to rapidly develop pieces instead of prematurely chasing tactics, and how it was possible to transform a lead in development into an overwhelming attack.
Of course, it all looks easy when Morphy did it - he was able to see combinations, at a glance, in positions where most players couldn't find anything at all ...
Games of Morphy are absolutely must know for intermediate player who do not want to be intermediate forever. I actually think that studying games of actual super GMs is absolutely senseless for intermediate player.
An interesting idea.
There was a pattern in 'older chess' of so many many games of top players beginning with e4 e5.
An extremely high percentage of master and GM games began that way.
Nowadays there's a better balance.
But point: why e4 e5 ....?
you'll hear different rationales.
Idea - the moves Nf3 by white and Nf6 by black are very important moves. In frequency in the first four moves of master games - you'll find they're played more than any other move.
Including by black on his move 1. Except against 1) e4.
Idea: 1) e4 is the most popular first move by white. Why? Because its the one good and best way to deter black from playing Nf6 immediatly.
Black doesn't want his knight 'bumped' by white playing e5 (yes Alekhine's defense is considered sound but the top layer of chess players seems to play to the effect that there's several better Preferable replies to 1) e4.
And black's first move - in reply to e4 - usually has an effect. An intended effect.
To make e5 by white less likely soon. Or immediately.