Do the items level matter on this game?

Item level only determines what level of stat modifiers can roll on an item. If it's a high item level then it can for example have a chance at getting a higher life roll on an item that would not be possible in an item with a lower item level.

If you've got two identical items except with different item level, does it affect your characters power in any way? No it makes literally zero affect to character power.

Unless you're trying to craft some specific level attributes into an item, you can ignore item level altogether.

If you're getting one shot regularly, make sure all your resistances are capped at 75% and that you have a decent amount of + to life on each of your gear pieces if possible. One shots do happen, especially against bosses or strong rare monsters, but shouldn't be super common, and rare if you're an experienced player.

You’re a bit late to the party Elon

Jk. Just wanted to make the joke

Yeah it does matter just because certain mods can only roll T1 (highest numerical stat) at item level 81-82. This pretty much only matters when you're late end game rolling item based to craft though.

Item level does and doesn't matter. Certain items can only drop at a minimum item level. An example of this would be a weapon that requires level 79 to equip it. That base that requires a higher level to equip it usually has higher stats. The more important thing that item level does is determine the highest level an affix can roll. An example of this is that for boots to roll +35% movement speed, they need to be item level 82. Different affixes have different minimum item levels. This does not mean however that an item with a higher item level is going to be better than an item with a lower item level. A level 35 piece of gear can be better than a level 82 piece of gear if the affixes on the level 82 piece of gear is terrible and the level 35 piece of gear has good affixes.

A high item level piece of gear can also roll low level affixes. This is why most ground loot in POE2 is so bad. White bases (normal) pieces of gear and magic items are more valuable than rare items. You can use currency on them that guarantees affixes with a high item level. Perfect orbs of transmutation and perfect orbs of augmentation will roll higher item level affixes than perfect regal orbs or perfect exalted orbs. In general if you don't know what you are doing it's also better to sell these orbs to someone that does know what they are doing in order to buy better gear. Low level skill gems for example can be sold for high prices that can give you an upgrade to your gear by buying gear off the trade site.

Elon says it matters

What are your defenses and elemental resistances? Where are you in the campaign? You say you picked them up at level 30 but if it was good enough then it might not be good enough now. You can check most of your resistances and such by pressing C

Item level determines what is trash and what isn't. You can't apply perfect currencies to low level items. So if you care about crafting then item level 100% matter.

Item level determines the pool of affixes available to an item. There is no concept of a 'gearscore'. A high ilvl item and a low ilvl one with the same stats have the same effect on your character.

In fact, at least in the first game, certain unique items can be more valuable at lower item levels because ilvl also affects the pool of corruption outcomes and lower ilvls can make certain desirable corruptions more likely to occur.

Yes it matters, higher item level - higher stats tiers

People are saying it matters

it barely matters, until end game.

Highest item levels CAN have a higher range of stats, so its "better"

but again, you only care about the stats. I have never looked or cared about the item level of anything, other than a few specific items (end game armour 84, end game relics for sekhams)

at level 30, you should only care about the stats you get. and again, higher item level means it is POSSBILE for it to roll higher rolls.

If you're getting one shot, it's lilkely because you dont have have good resistances, or life. 20/30% of each resistance is pretty good for that level.