[cmpb]

>we Homo sapiens outcompeted them and made the world better (in someone’s point of view) for Homo sapiens

I think what's coming into focus for a lot of people nowadays (i.e. the last 50ish years w.r.t eco conservation) is the idea that we are actually making the world worse (for humans) - that actually making the world better for ourselves necessarily includes limiting or reversing our out-competition of other life. While it may not be noticeable to humans that a single species has been driven out (even just out of a region and not necessarily to full extinction) over the course of 10 or 50 or 500 years due to human activity, that does still represent a change to the established biodiversity, which (many people believe) is likely to be net-negative for humans.

Reasons for these beliefs likely vary according to people's experience and interaction with the physical world. Personally, I find great joy experiencing wildness and nature, and I worry that my daughter will not have that. Others might be concerned that the loss of species incurs the loss of some aspects of nature from which we might be able to learn - that there was an opportunity to better ourselves that is now gone forever.