Ath'kethin
Elder Thing
"In the first tier (levels 1-4), characters are effectively apprentice adventurers." Not the emphasis. The book itself calls level 1 pcs apprentices. The book goes on to say that you're still learning the most basic skills of your profession. I don't really care about trying to say that someone is better than a commoner, or whatever. You're still learning. To me, that implies teachers and people who make sure you survive long enough to be a return on the time and energy spent training you. It just doesn't make sense to me to send someone still learning basics into life-and-death situations without some oversight from someone more experienced.
Sure. Whatever works for you and your group. It's your game.
To my mind, reducing the D&D level system to effectively levels 3-20 (or, if we're being honest about likely play, levels 3-15 or so) only compounds the rocket-fast leveling that is the 5e default. I see that as more of an issue myself.
YMMV, obviously.