Common vs preferred stock only matters in the event of same or liquidation if a company - preferred is paid out first. At IPO, both kinds of shares convert into the same public class of stock (with the rare exception of founders creating a special class of shares for increased voting power).

Functionally dilution should be considered in the full context of the financial outcome unless we are talking about voting rights and I wasn’t. For small shareholders the only real value of stock is money. If it is worth less money then its value has been diluted.