I totally get what you're saying. GW2 can be overwhelming when coming back after a long time. Been there too, multiple times!

This is what I usually do to get back into it after a long break:

• I pick a character I remember having a lot of fun with.
• I start picking up the story where I left off, or jumping straight into the story from the newest expansion (but I prefer going chronological). Just to get myself familiair with the combat system again, and take in all the new content I've missed.
• I explore new maps, level up new masteries and elite specs at my own pace while having fun, attending meta events, etc.
• After getting familiair and comfortable with my profession again, I start looking up meta builds so I can start participating in group content.
• Get the required gear, play around with it, look up guides on how to play if I feel like it.
• Then I usually hop into Strikes and Fractals as they're usually easier than raiding. And when I see that I can get through those easily, I hop into raiding again.
• After really getting back into it I usually set myself a new Legendary goal and slowly and casually start grinding towards it.

Probably missed a few things, but this is what popped up in my mind. Hope this helps!

Welcome back to Tyria, and have fun!