Should five per cent appear too small,
Be thankful I don't take it all,
Tax man: The Beatles 1966

Sustainability in terms of biomass, all comes from the sun.
In the UK there is a little under 1.2 acres of land per person and the carbon footprint for each is 12 acres, so we are using ten times what can be sustained by biomass. (Year 2000)
In the UK there is a little under 0.9acres (4434 square yards) of land per person and the carbon footprint for each is 12 acres, so we are using more than thirteen times what can be sustained by biomass. (Year 2024)

Published 2023The study estimates that plants on land produced 56 gigatonnes of biomass a year, as measured by its carbon content, in pre-industrial times, and that through farming, logging, the grazing of domestic animals and so on, people now take 17 gigatonnes per year, or around 30 per cent of pre-industrial levels. Today, plants produce an estimated 66 gigatonnes of biomass a year due to higher carbon dioxide levels, and would produce even more if not for land degradation, meaning that our current consumption sits at around 26 per cent.
https://www.newscientist.com/article/2391648-humans-use-a-quarter-of-all-the-biomass-created-by-plants-on-land/

Full Document Earth beyond six of nine planetary boundaries

If we left half the biosphere for all the other animals and wild things we need to reduce by 20:1 or let's say 96%