Holy moly I didn't know you could still play old RuneScape. I think I found my account like 8 years ago after not playing for a decade and I was like "neat" and signed off. Lol
From the sounds of it, your account would be on the "original" Runescape 3, rather than the Old-school Runescape this post is about.
Old-school Runescape is essentially a fork of a random backup they found of the game as it existed in 2007 that they released in 2013 after a lot of dissatisfaction about how Runescape had changed over that timespan.
None of the accounts/characters from the original game were migrated.
jagex is a very shitty company and shitty companies don't want money, they want all the money. they will kill this game eventually. I hate jagex, from jagex accounts which is just a blatant attempt to phase out 3rd party tools and lock people to their ecosystem (which also fucked me over because the new account system blocks my entire country) to their customer service which is horrendous.
now they're raising prices to appear more profitable probably to trick another prospective buyer and get tossed around again.
Hello! Just going to plug 2009scape, which is an open source version of old school RuneScape. It is available to download and play entirely offline with single player. It is just fine enough if you just want to scratch that age old RuneScape itch. :)