Am I being paranoid or gaslit?

Your husband needs to wake up. Bottom of the stair gates are a must. My 9 month old climbs the stairs. She also pulls things out of the outlets and chews them. Her most recent was the CO monitor. I've also caught her chewing the end of chargers.

As for the bath, remind him that drowning is the leading cause of death under 5.
I can't remember the exact percentage of those drownings happen at home, but it's really high. (Been working in aquatics for 20yrs). Tell him that drowning is silent and if he's not paying attention, it will be too late if something happens. Also the water only needs to be deep enough to cover their mouth and nose for them to drown (less than 5 cm or 2 in).

The toilet brush is usually a toddler concern, but if you have a cupboard under the sink or in the hall you can just leave it in there.

All of those are perfectly logical concerns to me. Babies find and put the most random shit in their mouths all the time. Bottom of the stairs is definitely a must, if they climb them they can fall down just as easily as they could if you didn't have one at the top of the stairs. Kitchen cupboards either need locking or you need a baby gate that's common sense. Your husband sounds wayyyyyy to lax to be caring for a baby.

My 9 month old daughter would absolutely eat the toilet brush if she discovered it. She 100% tries to eat the broom and they're the same texture
I'd also be scared to leave my child alone with him.
And to call a curious baby stupid for doing certain things that babies/toddlers do is wiiild

My 14 month old literally decided to paint our bathroom with the toilet brush this morning so you are completely correct, if the can they will. If he doesn’t want a gate on the door then he needs to sort it so the door shuts. You absolutely need one to stop the getting to the bottom of the stairs, we have it on our doorway into the living room rather than directly at the bottom of the stairs so that he can’t get to the front door either. It’s amazing how quickly they learn to climb or explore

Trust and follow your gut, at the end of the day all the things you have mentioned will only contribute to baby’s safety and not take anything away. So don’t listen to your husband do what you feel like is right for you and your baby.

All perfectly logical concerns and I have stories about my 2.5 year old that shows how valid they are!! We have a gate at the top and bottom of our stairs, one at the attic stairs and one at his bedroom door. We have removed toilet brushes and keep them in a press and any and all wires are in wires caddys out of reach. All of these things have been moved or implemented after an experience that made us realise just how quick and curious kids are. You are definitely not over reacting

You know what I realised the other day….men are completely different to women. I’m trying to find the simplest way to put it. Men don’t really change do they from a boy they get taller, smarter and wiser and that’s about it. When we grow our children we completely change our bodies change our brains develop we experience things they never will. So theoretically they won’t truly understand some aspects of us. But don’t get me wrong being gaslighted by someone you put your trust in sucks.

Found the percentages:
70% of toddlers is unsupervised (tubs, backyard pools, creeks/streams/rivers on the property, etc)
66% under 1 is in the bathtub

We have a gate on the living room door (leads to front hallway, stairs, and front door so that just covers them all) then another on the door leading to the kitchen. We don’t have one for the bathroom because it’s after the kitchen so one gate is enough there, we only really shut it if someone is cooking but she’s never unsupervised in the kitchen so bathroom isn’t a worry in that sense. All the kitchen cupboard doors have locks on them and we don’t really have any exposed sockets and wires but if you’re in the UK plug sockets themselves are safe, though I still wouldn’t let them play with cables or plugged in devices

Those concerns are logical babies don't know to not touch the toilet brush or an electrical outlet. It doesn't mean they are not smart it's because they are babies and they have a lot to learn. He is being unreasonable and selfish to not be concerned with the babies safety.