If you're going to make the claim that people hold intrinsic value, people are going to challenge you for proof. Holding a door open for someone and asking questions doesn't necessarily indicate value. It could indicate personal interest. Empathy. Projection. Self-interest. The concept of altruism doesn't necessitate the belief that other life holds value at all. Altruism by its definition is giving without the expectation of return.

I think you make a good point re culture and tradition. Humans like many "valueless" activities. Some of these are hardcoded into our psyche through evolution. Some are for sentimental reasons. Some are religious. Some are enforced. Some are situational. Etc. I am not suggesting we eliminate those. I am simply agreeing with the top comment which is that we cannot force people to place any value on them. Some people do not see value in those traditions (or in other people). There is no objective way to prove them wrong.