Individual contributions, both large and small, are together by far the largest source of funding for campaign spending at the federal level. It's certainly possible that this is different at the level of the California state legislature but I see no reason to think it is without evidence to the contrary.
Summary: It feels like we have a government that governs on behalf of those with money because those with money vote first in the fundraising "election" that happens even before a primary election. More money is more votes in the "election" that mattes the most. Those with money get to filter candidates first.
edit: Just because money comes from an individual and not directly from a corporation doesn't mean it isn't a pro-corporate/"corporate" contribution.
Not to say republicans represent people either, republicans unapologetically back unchecked corporate power. Democrats try to serve two masters.