What is the importance of equity?

Hello all,

Perhaps a basic question for some, but I’m struggling to understand the usefulness of metrics like ROCE and debt-to-equity.

I understand equity, however up to now I’ve just taken a look at it to ensure that a company isn’t in a net negative equity position (net liabilities do not exceed net assets).

Outside of that, I struggle to see its importance. Some outlets online tell us that it’s to see how well the company is utilising shareholder investment, but the only time a company gets anything from shareholders is during the IPO process, or when they increase the amount of outstanding shares.

It would be fantastic if someone could explain the usefulness of equity in that sense.

Thanks in advance.