The FPTP system is what straddles UK politics and is self perpetuating.
A Tory government with a large majority of 80+ seats is coming to an end and is likely to be replaced by a Labour Government with a similar large majority. The hope is Labour will do a better job for the majority of the populace, but there is no guarantee.
'Events' (outside the governments control) as Harold Macmillan explained can be instrumental in ruining everything; as Suez did for Eden, Iraq for Blair (although he got 3 terms), Financial Crisis did for Brown, Brexit for Cameron and May, Covid for Boris; Liz Truss (for herself really) Money Markets; Small Boats for Sunak.
When Starmer takes over there are no shortage of internal issues, like cost of living, housing, NHS waiting lists/dentistry etc., but there are enormous external 'events,' Wars, those continuing (or further likely to break out) in eastern Europe, Middle-East, etc. mass migration on a hitherto unimaginable level, and of course dealing with climate change.
Why do we persist with a FPTP system? Because there is a 'gut' feeling, than when the country is facing crisis, or when sh** lands from a great height and we didn't see it coming (you can ask why again some other time), the government has to be able to act quickly and it is only with an overall majority (gained by FPTP) can this happen.
Where does this 'gut' feeling come from... law making based for centuries, mainly on precedent.