> it up into "social" policies and "economic" policies.
I understand that inclination but you cannot separate economic and social policy.
Example: consider post-WWII development in the US. The GI Bill gave cheap loans and college education to returning servicement but not if you're black. The rise of the automobile lead to the explosion in suburbs, which became completely car-dependent. These suburbs and the required infrastructure (eg roads) were government subsidized. This allowed some to build up generational wealth.
In building those roads (and the Interstate system) these tended to divide communities along racial lines and in many cases wiped out minority communities.
Further you had redlining.
Once segregation was officially outlawed you had a bunch of communities that became effectively segregated because black people couldn not afford to live there (because restrictive zoning drove up prices) but black people had been denied the ability to build up wealth.
That's an example of what people mean by systemic racism.
Likewise, economic policy creates over-policing and mass incarceration that predominantly affects the poor and economic policy has made sure that black people are disproportionately affected.
> Democrats are a socially very left
I disagree. Biden was the architect of Bill Clinton's 1994 crime bill that ushered in mass incarceration and over-policing shows where Democrats stand: in the same place Republicans are, which is protecting capital and capital owners.
Literally the only reason people accuse Democrats of being very far left is the support of trans people. I would urge people to really examine their feelings here and really ask themselves why they think not being transphobic is an extreme position.