In your worldview, pain and suffering are simply chemical reactions taking place in a bag of chemicals.
You're trying to decide that for them but you don't and it's dishonest misrepresentation. What does that say about you? In fact, we are complex animals with complex brains and inside, we do run with complex biology and neurology, that inside, involves electrochemical processes. Organs are also involved in chemical processes and that's how you breathe and digest. Medications also work due to those processes. The best explanation for that complexity so far remains long evolution, genetics, descent with modification, natural selection. And the evidence for evolution is overwhelming, it's a discovery, not a claim. https://en.wikipedia.org/wiki/evidence_of_common_descent
Why would that be wrong? When baking soda reacts with vinegar do you get upset?
Is that a sane proposition? More another dishonest straw man.
Do you say that it is morally wrong?
Physical processes are not about morality. But our mind, a product of our bodies and of neurology, is capable of symbolic thinking. We are capable of emotions and even infants can perceive some types of obvious injustice. Other animals too, social animals have some simple rules and empathy, derived from their condition. This includes forms of communication. Not getting harmed when it's not needed is advantageous to survival.
Your view of morality does not comport with your view on origins. In my worldview, people have intrinsic and objective value, since they are made in the image of God.
Your deity has been found to not be an objective concept and that is easy to demonstrate, all the literature of Abrahamic theologians are also a witness of that. Humans are also known to create their dieties throughout history, much before the history of your particular deity, that may itself be derived from former deities (Ea is a contender). That's how human traditions work. Pretending that you're made in the image of your deity is a justification to attempt to explain why the deity has obvious human attributes (the obvious answer is that humans imagine it).
It is because the Bible is true that we can call pain and suffering "bad."
Nonsense. When you feel pain, you already know that it's bad. When you see someone suffering, you may also be able to perceive that something is wrong. What does "the Bible is true" even mean? It's a collection of collections of human writings and some obviously contain false claims.
In the evolutionary view, they can never be more than chemistry.
Who is they? People? I already explained above, about your dishonesty and ignorance. We are indeed still chemistry though, if you bathe in a strong caustic solution, you'll dissolve, if you're exposed to enough heat, you'll burn. Even when we deny our nature, those processes actually work.