My 2p.
"Animals I've been told don't see colour anyhows."
Animal is a catch all that covers all vertebrate and a big hunk of invertebrate life, that means mammal, bird, reptile, amphibian, fish, plus about eight different flavours of invertebrate. Many, animals have colour vision, and there are a lot that have colour vision as good or better than ours.
Many of the mammals that people hunt have dichromatic colour vision, meaning they have two types of colour receptors while we have three. Not all prey mammals see the same colours, so the colours that a deer can see are not entirely the same as can be seen by a rabbit. Squirrels and deer have vision similar to humans with red/green colour blindness, hence the use of day-glo orange, but even that is often broken up so that the human outline is somewhat camouflaged. Birds in general have excellent colour vision. If you want to scare every creature for miles, try wearing something in solid bright blue.
Camo clothing may not give particular people in a particular place any discernible advantage hunting or approaching their target animal, but taking hunting and stalking more broadly there can be no doubt that it can confer an advantage, particularly when animals are encountered at close range. Not only can it help conceal you from the main target of your attention, but also from other animals which if startled could sound a warning and alert your target.
My experience is that camo can be quite location specific. Get it wrong and it isn't much if any better than just wearing drab solid colours. Get it right and you can blend in with much less effort, startle fewer alarm species and get away with being caught in the open more often.
Many of the patterns from the last 20 years aimed at hunters have been aimed at the US where hunting is often a late Fall or winter activity and where the dry/cold turns the landscape brown and grey. In the UK and I would imagine in other places with a milder maritime climate, things are pretty green all year round and you do tend to stand out rather a lot wearing one of the black/grey or orange/brown based patterns.
Covering the pink hands and face makes a huge difference, although you could probably get away with any solid colour that matched the tone and colour of the background.
If all you are doing is wishing to watch an animal, it may not be worth the extra cost, but getting a clean shot with a bow, rifle or camera is more demanding and if clothing can help, its a card worth playing.