You are totally mistaken.
Please reread the appropriate Schedule:
SCHEDULE 16
Associations: exceptions
Single characteristic associations
1(1) An association does not contravene section 101(1) by restricting membership to persons who share a protected characteristic.
The relevant point is that all members of an association must share a protected characteristic (PC).
If there is more than one PC then all members must share all of the PCs. So, in your example, if you were taking Jewish to mean a religion rather than an ethnic or racial group then you could certainly have a club solely for black people of the Jewish faith. That would be fine.
You could not though have a club for people who were either black or of the Jewish faith as some of the members would not necessarily be black and some would not necessarily be of the Jewish faith.
If you are talking solely about race or ethnicity then that would not work either. A club for black and Jewish people would be fine if all the members were both black and Jewish (just in the same way that you might have black Britons or British Jews or Irish Travellers).
In contrast, a club where you had black people and/or Jewish people would not be lawful as there would be people in the club who did not have both of the PCs.
It would be no different from having a club for white women and black men.