Yeeeaaaah, no. There hasn't been a "way left" of note in the US since... what, around the start of the cold war? It's been longer than my lifetime. We used to have communist/socialist parties that people actually talked about, and the first socialist we've had of note in the last few decades has been bernie (and in most areas, far left he is not), so far as I'm aware of. The dems are notably centrist compared to, y'know, actual leftwing parties in other countries. There's been polarization, but in terms of policy the left in the US has not changed much in, well. Like I said, longer than my lifetime. Better than 20, 30 years. Sanders is the closest to a shift of any meaningful visibility I've seen in my personal ever, and he's still mostly just saying, "Hey, maybe we catch up with the moderate left in other social democracies?" The healthcare attempt (while much better than before) was still a conservative riddled mess in a lot of areas, the gains on social issues have been stuff that's been fought for for longer than I've been alive (and a hell of a lot further back than '94), militarily we've only barely started maybe drawing down on adventurism (much of which significant chunks of the democratic party cheerfully supported/supports)... there's just kind of a list. Outside of homosexual marriage and maybe some environmental/regulatory issues there hasn't really been meaningful leftwards successes that I can recall until the last few years, and a lot of areas the dems have, to all appearances, moved at least as in lockstep with the american right as before. They haven't been moving left so much as standing still as parts of the republican party goes insane.
Honestly, a lot of the support that sanders is getting is just from people that've gotten fed up with the lack of a notably left option over the last few decades -- there's been plenty of democrats, but most of the ones nominated and elected to president et al have been largely centrist, not really trying to rock the boat to any large degree. Somewhat understandable considering the realities of compromise they were trying to play with for a while as the conservative coalition started going utter bugnuts, but still. Some folks have been getting tired of the incremental and often eroded gains in the realm of welfare, education, etc., which is where a fair chunk of sanders' base is coming from.