In the case of the OD&D and AD&D ranger, it pretty much was just stuck together. I don't remember who invented the class - it was in The Strategic Review if I remember correctly - but it was "fighter" + some minor spellcasting to make it like Aragorn...
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It was in Strategic Review, but they got amazing spellcasting (gaining cleric and wizard spells, and if you reached higher than 14th level it really started to pile up - I don't think there was a level cap on the level of spell they could eventually cast.
In addition they got tracking ability, surprised less often, surprised others more often, +1 per level damage against pretty much all humanoid bad guys and giants (collectively called 'giant class'), plus gained a number of extremely cool followers (in the strategic review you could even get a young gold dragon follower!)
They also got the ability to use any magic items connected with clairvoyance or healing (a real 'Aragorn' connection there).
Oh yes, and they started with 2HD rather than just 1HD, but you could never have more than a few (3?) working together.
So... much more than just a fighter with minor spellcasting! The spellcasting was toned down for AD&D hugely, toned down again for 2e, toned up slightly for 3e, toned down again for 3.5e and eliminated in 4e. I'm happy to see it make a return again.
Cheers
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