Cloudflare is in the S&P500. If you have a 401k diversified in broad market indexes then most likely… you are a shareholder.
...and the top 10% by wealth own 90% of the stock market.
So even among the half that do have retirement savings in 401ks and the like it is on average very little compared to how much the truly wealthy have invested.
Also if you buy a index that invests in a stock that doesn't make you a shareholder. Vanguard, for example, would still be the shareholder in the company's records, not the people who invest in Vanguard's index funds. Of course, its stock price movements will have an impact on your holdings if the stock is in the index but legally, you are not a shareholder.