So, about a year and a half ago, I moved and the box that had my Iron Hills in it was stolen and I've been looking for a new army to play for about a couple weeks now. Is there a downside to not playing cavalry? I'd prefer infantry with a decent amount of bows. I was looking at Numenoreans simply because with it's lack of models, I wouldn't be enticed to buy the entire range. Second pick would be Gondor, but I'm not enitrely sold on their outdated look. Last choice would just be to nut up and rebuy some Iron Hills

Cavalry is certainly not compulsory - the latest Grand Tournament was won by two full infantry armies. I personally typically like having a few fast models in a list to aid in scenarios that require mobility, but there are ways around it: ample Might and access to heroic march allows you to cover distances quickly, or plentiful numbers to allow you to hold and go after multiple objectives, or sufficient shooting to deter the enemy.
I should note that Númenor is likely to get some reinforcements in a future expansion focussing on the Last Alliance, but I wouldn't suddenly expect a great host of new figures. Anárion is certainly on his way though.

Nice, thanks man. I've seen a few ebay listings with bows and spears in bulk for decent price and it's good to hear that they'll probably cover the LA in a future book

So, infantry heavy armies can be competitive? Great, because I always tend to overextend myself with fast forces like cavalry. Are there any races I should try to avoid as a beginner? I'm a newcomer in Tolkien/fantasy-themed wargames, I'm more used to 20th century ones and am not that familiar with what the most competitive races are.

I play a lot of infantry heavy armies, and if you play well, they can really motor. In this game cavalry are fast, and on the charge they are the rock to infantrys scissors, but without the charge they are just overpriced infantry. So you need to double down and have a character to babysit your cav. (to call heroic moves) Infantry on the other hand don't mind charging or being charged. It's all the same.

As a newcomer I'd avoid Dunedain, or any hero only force really. And any army with only 2-8 units to pick from. For newer players I'd recommend the 'big' armies.

Evil LOTR
Mordor
Isengard
Angmar (though a bit of a finesse army)
Moria
Barad dur
Harad and friends

Evil hobbit
Dol Guldur (often tricky tho)
Azogs hunters
Azogs legion

Good LOTR

Gondor
Rohan
Rivendell
Lorien
Dwarfs

Good hobbit

Thranduils halls
Iron hills
Erebor

These are the armies that have lots of love, lots of options and as a result, the most powerful armies, and often the most forgiving.

If I had to narrow it down for imo the best armies for a beginner to learn the game with I'd say

Evil
Mordor(heaps of crutches to lean on and can play any style you like)
Isengard(Rock solid and their army bonus is more forgiving than jesus)
Balrog Moria(biggest reddest crutch and point and click.)

Good
Iron hills(oof)
Gondor(High courage, plenty of nasty huge characters)
Rivendell (See Gondor)

Hope that helps

Thanks for the in-depth answer! That's pretty convenient, I like Isengard themed armies and dwarves in general; I think I'll build the former as a first army to try playing the game a little, since you describe it as forgiving, and a dwarf army later on if everything goes as planned!