Explain Like I'm Five

Right, and modern US liberalism isn't general liberalism. Plus, those distinctly modern elements absent from general liberalism of active non-market interventions by the government to protect the market from failure, provide a safety net, provide access to education & healthcare, provide public services to reduce inequality, protect the environment, etc, are social departures from capitalism, are they not? That position aligns better with social democracy

a social, economic, and political philosophy within socialism

social democracy aims to strike a balance by advocating for a mixed market economy where capitalism is regulated to address inequalities through social welfare programs and supports private ownership with a strong emphasis on a well-regulated market

If anything, modern US liberalism conflicts more with your earlier assertion that

Liberalism is basically capitalism

Whereas general liberalism is largely indifferent to economic system, modern US liberalism favors a form of socialism.