I think it slightly improved after the first 5 actually. The first 5 episodes were just her at school, and after she leaves she starts adventuring a bit. Granted I'm not sure I'd recommend watching it if you didn't like the first 5 episodes either way.

A lot of the humour of the main series is ultimately derived from the party dynamic in my opinion, so I absolutely see where you're coming from in that regard, and to some extent I'd agree with you. Later on there are some Axis Order related shenanigans, and a tighter focus on Yunyun's dynamic with Megumin, but it struggles to reach even the baseline of the main series' humour for me.