Good question. Anarchism and Autonomous thought is big on the left but that's all extra-parliamentary, the SPD has been New Labouresque for literally ever now (Schröder at the latest) and if it isn't it's doing clientele politics for random strong union factions at the expense of everyone else (see e.g. coal subsidies) and forget them ever caring about Lumpen. Die Linke is in practice SocDem and the likes of MLDP and DKP are irrelevant splinter cults, both claiming to be Trots and accusing the others of being Stalinists you know the type.

The Greens have never been a left party but are plenty socially liberal, the FDP likewise though they like to fish for first voters by pretending to be left-liberal instead of neoliberal pretending to be ordoliberal. Oh the Greens have a way better track record not being in bed with fascists, their first party convention was full of "Not enough is being done for the German forest" types but they all got kicked out. Probably a reason why they emphasise the social liberal part so much, it acts as a repellent. And it's not like they'd oppose left politics it's just that they care about random hamster habitats more than social housing, they themselves are either driving SUVs (hopefully EV) to organic farmer's markets or sell shit on that farmer's market.

Heck parts of the CDU in places sometimes out-left the nominal left when they, occasionally, probably by accident, remember what the C in their name stands for. Mostly individual welfare stuff of course macroeconomically they're capitalist AF.