Yes, I'm aware that this isn't a game where you can easily make things impossible with a sub-optimal starting setup. I just want to make sure I didn't accidentally pick something untenable (except maybe in comparison to life-halfings...).

Picks:
Nature-5
Life-4
Nature Mastery
Artificer

Nomads

The spell choices were mostly over wanting to make VERY well-wrought cities (...nomads? Cities? More like ex-nomads...). Life was a shoo-in, and the choice between nature and sorcery was ultimately about what kind of combat I liked. Nature got the nudge in extra spell points because it actually had more spells that appealed to me than life. As for Artificer...I'm liking the thought of itemcraft perhaps a little too much...

Well, I'm not that experienced at Master of Magic myself but I think you'll be fine. I played as Nature / Nomads and had a lot of fun. I think Nomads are considered one of the weaker races but they have some cool unique units (rangers are really useful) and Nature is a lot of fun. I haven't used Artificer myself though.

One nice thing is that Nature has a lot of summons so you don't have to rely on standard troops as much.

The main problem with summons though is their cost to maintain and cast. They really deplete your available mana and your income mana and the units cannot gain in exp like normal units can.

Well, yeah. But they're COOL.

Also, faeries are brilliant disposable spam summons-actually hit quite hard via missile until you're right up the top end, relatively cheap, and you can slow your city unit production down while you use them.

Life can be a very good spell school, stacked blessings can turn a single decent unit into heroic proportions, and as for doing it to a high-class hero..
Also star fire is brilliant for dungeon-clearing

You're probably better off with an additional spellbook instead of Nature Mastery, or with the Summoner special if you really want to focus on that.

I've never been a fan of any of the color mastery picks. Sorcery Mastery is easily the best, IMHO, simply because there are usually so many more Sorcery nodes on most maps than Chaos or Nature. I find any of them to be just plain inferior to Node Mastery, even with the extra spell books required to take it.

That said, the OP's starting setup seems fine. Nomads aren't a bad race, even if they're not the best either, and Life and Nature tend to work well together.