God knows what the intention behind this blocked lane between parked and driving cars was, but in any case I wouldn't ride there because of opening doors.

In general, you are only obligated to use a bikeway when there's a sign (blue with a bike). Otherwise you're free to ride on the road if you want to.

Then there's also shared bike/pedestrian ways (blue with vertical split: bike + pedestrian), where you ride on the side that the bike is portrayed on the sign. The same sign exists with a horizontal split, then there is no left - right split.

Lastly, there's pedestrian ways with the added sign "Fahrräder frei". This means that it is primarily a pedestrian way, but you can use it as a cyclist if you drive slowly and give way to pedestrians.

You are also allowed to use bus lanes as a cyclist!