thoughts on the Sicilian

No, never use it on your level unless you want to learn it ( quite literally learn it ), its the most dynamic opening and not ideal for beginners, i'd go with scotch gambit since i play it too and its relatively simple to learn

500 Elo might be a bit early to learn anything other than 1.e4 e5 or 1.d4 d5. I mean I play it all the time, but I am 1200 Rapid 900 blitz. It is a huge undertaking to use that opening properly as it is a massive broad base of opening theory. Nothing stopping you, but it will be a lot of work for you. The short theory is contest the centre so white cant play 2.d4 and keep a classic 2 pawn centre. The middle game is white attacks kingside, black attacks queen side. But the methods and lines used are massive. White may or may not castle either side, black may or may not stay in the middle or castle king side. Most people don't know theory to play main lines, so understanding what you are doing is harder as you are learning against rubbish.

Play whatever you feel you might enjoy.

At your level (and right up to the 2000 level), your most important asset for improving your chess isn't your tactical ability, your strategic judgement, or your memorized opening lines. Your most important asset is your enthusiasm for chess and your enjoyment of the game. That's what keeps you hard at work improving your play. If you stopped enjoying it, the effort would taper off.

So protect that asset by playing whatever you enjoy playing.

My own preference is for unbalanced openings, where both sides have advantages and both sides have disadvantages. It makes for an interesting game.