Yeah pretty much. The astral era quests are the continuation of the Main Scenario story. You will need to get those done eventually before you can get into the Heavensward areas and story.

While I will first say that you really should do whatever interests you, I would warn you that out of all the end game content the full relic quest is very long and a huge time sink.

There are so many things you can do in this game. Beast tribe stuff, Hunts, Gold Saucer games, crafting and gathering..... Its a long list. Try stuff out and do whatever takes your fancy. You can also look at starting to unlock the Crystal Tower which is the 24 man raid and can reliably be done with the Duty Finder.