Species of beetle or of fungi or of any other kind of living beings may look very similar, but nonetheless they may differ in their ability to synthesize various chemical compounds by using various enzymes that may not have equivalents in other living beings.
The popular literature is full of triumphalist b*s*t which makes it appear that most basic sciences, like physics, chemistry and biology are solved, but this is extremely far from the truth. We are still a few decades away from being able to understand well enough how a living being works, so that we would be able to replicate similar processes for making whatever we want.
Until then, every kind of living being which disappears is an irreversible loss of precious information, which may have saved an unpredictable amount of time in the future, which will be needed to rediscover similar results with those produced by natural evolution during millions of years.