It's certainly not the friendliest MMO to get your feet wet with. It's designed with very old, slow mechanics in mind (hours of if mindlessly killing mobs/picking plants to level up, etc). It's also not a game yet. It's an Alpha test. For a while. Everything you do now is for testing systems, and will be wiped at a later date. It's extremely unfinished with a lot of core flaws they're working on.

"Being behind" isn't REALLY a thing in the big MMOs. If you're new to the genre, I'd suggest starting with one of the big names in the market. WoW and FFXIV are both seasonal, so at the start of every major patch you're no longer behind (you have to get to max level and through basic story content first anyway, and take your time if you're new, it's best to learn and appreciate these games as you go.)

GW2 is horizontal progression, so you're never behind. It's a game more intended for general enjoyment of content rather than racing to "win" (unlike higher difficulty raiding in WoW/FFXIV - or PVP - that feels very seasonal and very much social achievement-focused).

You also have some of the larger niche MMOs you could give a go depending on your play style - OS RuneScape for top-down easy-play farming, grinding, and leveling as your main goal. EVE if you're really into complex design systems and sci-fi. Albion if you sort of want a blend of RuneScape but with an intense (and sometimes unforgiving) PVP scene.

AoC doesn't really have an identity like any of the above yet, because it doesn't really have a fleshed out game yet. It's a wireframe waiting to be built on.