The Cambridge Declaration on Consciousness already says that they're conscious. The idea that non-human animals lack experiences is a fringe view nowadays.

While Cambridge declared them conscious there is no definite proof that they are in fact conscious. It may be healthier to view them as conscious but there doesn't seem to be a strong public consensus on the matter.

In most countries, there are laws against cruelty to animals, however inconsistently or hypocritically applied. Having these laws presupposes a strong public consensus that animals are conscious in the sense that you're asking about.

there is no definite proof that they are in fact conscious

What are your standards for such proof?

Proof would need to be more than declarations or legal standards, which can be influenced by ethical considerations rather than scientific consensus. Public consensus could, for example, be swayed by robust neuroimaging studies showing gorillas having neural patterns similar to those seen in conscious experiences in humans, or a scientific breakthrough that redefines the way we understand consciousness as a whole. AI can mimic reasoning and behaviour without consciousness, indicating that complex behaviour alone isn't sufficient evidence for consciousness.

Do you think that linguistic concepts and a psychological ego are necessary for consciousness?

Could you define ‘conscious’ please? They seem to meet all criteria I can think of. (Unless they are asleep/unconscious).

Do they experience the world like we do (see colours, feel touch, hear sound etc.) or do they process the world like a machine with complex maths that just gives the illusion that they have an inner experience

Oh this is a P-zombie question. Yeah, I’m selling.

Has it been proven humans are conscious? It's a vague term

I wouldn't say so but the general consensus is yes