Why does the economy require growth? Biological systems can find equilibria, why can't an economy do the same?

Economy in general doesnt require growth.

The economy we were born into, the level of material production, business, amenities etc and how we run things, does.

It can find an equilibrium at some point, but it will be blood and people who think they should have robot servants and food delivery wont like it. As for the time it will be achieving that equilibrium, it will be painful.

Because bigger number, obviously.

All economies do not inherently rely on growth. It's just that capitalists have brainwashed themselves into believing capitalism is the only type of economy possible and that growth can go on without bound literally forever.

It's exactly as stupid as it sounds.

Capitalism requires growth. If your sales aren't growing your stock price goes down.