>>534361331
No problem anon; I'm a bit envious of you experiencing terraria for the first time. It's quite fun and you have a long road ahead of you filled with possibilities. Exploring the surface is a very good idea, and don't be averse to building little outposts that you can dump your inventory in so you can keep exploring. If you keep an eye out, there should be small veins of ore in forest biomes very close to the surface, which can be either copper/tin or iron/lead. I recommend mining the latter, as it's a decent step up from wood gear, and is used in a variety of things from armor & weapons to crafting stations and tools. I will suggest though, try finding a desert and making armor out of the cactus there.

Also, don't worry about bosses destroying terrain, that's not a thing. It's only stuff like player-thrown bombs and dynamite that can break blocks.