The first-place party at that time was the Nazi party.

Hindenberg trumped Hitler by nearly 6M votes. The Nazi Parliament comprised roughly a 1/3rd of seats. Well short of a working majority, absent a host of like-minded Germans in the Friekorps and the liberal aristocracy.

Hindenburg had been ignoring the parliament for a long time by then, and he only wanted it to support him in order to prevent a potential civil war.

Thank goodness we didn't end up with a Germany cleaved down the middle. He really dodged a bullet.

Hitler was seen as a simple idiot they could place to play as a chancelor

Yes, in the same way that Trump was seen as a bumbling chud whom Hillary could catapult over to victory in 2016. Or when Bush Jr or Reagan were dismissed as lightweights during their first runs. There's always this general disregard for popular politics, right up until it bites the incumbent in the ass.

the chancelorship and the police were enough for him to take over the country completely

The chancellorship, the police, and streets full of brown-shirts imposing martial law after the burning of the Reichstag. Of course, the German state had made such a fetish of Communists as traitors and saboteurs and foreign agents that Hindenburg went right along with the coup for fear of being labeled one himself.

That was the real power of the Nazi movement. The ability to, at any moment, single a person or a neighborhood or an ethnicity out as a scapegoat and unleash a wave of violence against them.

In the modern moment, we have the same problem in the form of right wing religious and media organizations. And we've got a modern day Weimer Republic that simply goes along to get along, rather than putting up any kind of resistance or organized opposition.