Welcome back.
Quitting for 13 years must be a world record but they always return thats just How rs works

So yes i would advise you to play Osrs its gonna be very nostalic.
As star said if you just want to play your self and figure out the game then about 10m cash should be plenty in the start.
If you want to skip all the beginner stuff then you can just Pay People here to do all the stuff you dont like haha.
Top tips.
Set some goals for levels you want/ places you want Unlucked.
I always suggest New players to get into questing as its the biggest unluck in the whole game. Quite big job tho.
There a 2 different account types now.
Regular accounts: they can use g.e / trade with others.
Ironman: can not use g. E / trade.
Ironman is much more dificult as you really need to know the game where to gather items.
I would personally advise you to make a regular account before gettin into iron.
Feel free to pm me for questions etc while you start up i do My Best to answer