WHY is the universe here?

Well, that is the ultimate question, isn’t it? Why is there ‘something’ rather than nothing.

One possibility is that ‘something’ is fundamental, that ‘nothing’ simply doesn’t and can’t exist. The quantum vacuum may have always existed. If the quantum vacuum is eternal, the energy-time version of the uncertainty principle could give rise to - however improbable - our universe and possibly countless others. While physicists are generally skeptical of the anthropic principle, it’s possible that it applies.

Einstein considered time and space to be the result of matter/energy - gravity IS time and space - and matter/energy produces gravity. So time and space may be a consequence of ‘something’ rather than ‘nothing’ and not have any particular greater significance.

The assumption that ‘something’ has always existed of course, isn’t particularly satisfying in that we cannot determine what that ‘something’ is. Occam's razor would imply the quantum vacuum over a deity. But, who knows?