I remember the magic I experienced the first time I played RS back in 2007. The game was mind opening. Although I only had a free account, but nevertheless had a blast getting my first Adam and Rune full gear.
How is OSRS for you now? What are you enjoying the most. I wonder if I will get the spark back if I try it or if I'll be overwhelmed of the options of things to do
It's as good as it used to be. I've enjoyed doing quests and fighting bosses. Grinding is slow but tolerable if you have a video or podcast you wanted to watch or listen to. Coming back as an adult is a different experience. You'll find yourself being a bit more directed in how you play and it's easy to optimise the fun out of the game. It's decent on mobile and I have heard of people fighting endgame bosses on their phones.
It is easy to get overwhelmed on p2p. My advice is you set a goal and go for that, or you pick a thing you really want to do and just do that and let the game slowly open up from there.