Diablo 2: Resurrected has been confirmed to be able to use old save files from the original Diablo 2, meaning you can pick up where you left off.
Diablo 2: Resurrected Will Accept Old Save Files From the Original
If you’re looking forward to the Diablo 2 remaster, but afraid you will lose progress of the original, fear not, as Blizzard confirms you can carry on your adventure where you left off. The old save files of Diablo 2, will work withDiablo 2 Resurrected.
This new detail was confirmed by game producer Matthew Cederquist who shared withIGN Middle East, that this feature was actually a happy accident:

Yes! Keep your old save files. Back when we were working on [the remaster], we wondered if the old save files would work, so we kind of shoved it in, and it worked! So yes, your local singleplayer save files will carry over.
This means you can return to your favourite characters but with a new remastered experience with updated graphics, improved networking, and cross-progression with the remaster’s console releases.

Previously the developer shared that Diablo 2 Resurrected would not be replacing the original Diablo 2.
Diablo II Resurrected will include all seven classes and all of the memorable bosses as well.Classesinclude Amazon, Assassin, Barbarian, Druid, Necromancer, Paladin, and Sorceress. The developer doesn’t plan to change any of the game’s itemisation or balancing, meaningDiablo 2will have the same replayable experience it had when it released 20 years ago, but with an updated look.
Diablo 2 Resurrectedwill be coming to Nintendo Switch, Playstation 4, Playstation 5, Windows PC, Xbox One, and Xbox Series X later in 2021. Also, a “technical alpha” is coming to PC soon, with sign-ups now open at Diablo2.com.
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