The main way to increase your character's strength is to get stronger spells. You do this by collecting the necessary crafting ingredients then crafting the new spells in the settlement.
All NPCs are on the same tier as you. You can rescue/unlock more by finding "Rescue NPC" missions in different region types (junkyard, abandoned town, etc.) throughout the game.
I meant strength as in carrying over from one continent to the next.
Well, what NPCs are considered the bronze age as opposed to other ages? I unlocked the very first one. I could unlock the others just by finding the missions in other regions.. so I could do it all on the same tier then?
Yes, in terms of one continent to the next enchants are your main buff. However, it's a fairly slow build.
In terms of NPCs, "Bronze" is not an indicator of quality. Bronze Age refers to a historical time period (aka, Rome/Greece in the real world -- Macedonia, all that good stuff). The characters from various time periods are all roughly equivalent, although they do have different innate stats and graphics and so forth. So it's giving you more options and more choices about how you customize, but it's not giving you generally-better options in characters. You won't stop using ice age folks because you now have bronze age folks. But you might take a bronze age guy somewhere that you wouldn't take your main ice age character, for instance, or vice-versa.
You know, I wouldn't mind seeing some sort of way to sacrificing unwanted enchantments to help boost you to your next, or combining them to get a new random enchantment. After a while the damn enchantments bars get so cluttered and large it grates my teeth.... I know I can just drop them, but for how much hunting and gathering you do to get the damn things.... well it be nice if I could actually do something with them instead of just throwing them away to simply clear the bars.
Yep, as Penumbra noted it's something already in mantis and that might be nice down the line. However, it would accelerate your enchants-acquisition-rate which isn't something we'd really want to do at the moment, so that complicates it. It's basically on ice until sometime after 1.0. If the number of enchants goes up a lot, then it might make good sense to allow players to increase their rate of acquisition in this way so that they can keep up. We'll see; for now, just dump them for sure.