Have you ever read the full story of the Bismarck? It’s a comedy of errors and unfortunate events for both the RN and the Germans. For example, Hood and Prince of Wales were initially in a strong position, set to cross the German T, and an expected intercept time / position that would have a rising sun behind them, which would have made optical range finding more difficult. They also had destroyer escorts, which could have been quite useful in an engagement. Then contact was lost… Hood and POW had to race to intercept, leaving the destroyers behind, and essentially reversing the desired positions. Naturally the British cruisers that had been shadowing the Bismarck showed up for the battle…and did absolutely nothing.
Then of course, there was the matter of the lucky torpedo hit, made possible by the German admiral sending a long radio message, believing his tail was already in the ringer when the British had lost contact again. Naturally the British initially screwed up locating the Bismarck for a bit after that, and had nothing in position that could effectively engage except aircraft. So what do they do? Try and torpedo a RN cruiser in a (thankfully failed) friendly fire incident.
Re: the Bismarck’s design, there was good and bad. It essentially utilized a spaced array armor system, which was a slightly beefed up version of what was on the Scharnhorst and Gneisenau. While it was extremely difficult to put a shell in its machinery and magazine spaces due to the layout, there were potential vulnerabilities due to the main armored deck sitting so low in the ship. IIRC, the British got their hands on some design details after Bismarck was sunk and a few crew members were rescued with it. Their remarks weren’t particularly flattering, and noted that it would be especially vulnerable to semi-armor piercing munitions. While these would fail to penetrate the main armor deck, the shock would likely create major problems for gun mounts, machinery, etc.
