A teacher can be supported by volunteers - a discreet, hardworking, pleasant person to have around who can volunteer a couple of hours every week to come in and read or do other jobs is always really welcome.
Many schools make the reasonable stipulation that volunteers cannot be in their own child's classroom, and of course any volunteer is expected to conform to the same standards of confidentiality etc that a staff member would. We do occasionally turn volunteers down if we feel that their main aim is not to genuinely help but to gain admission to the classroom to 'see what is going on'.
A teacher can also be supported by the PTA in making their classroom, and the school, an exciting, pleasant and cheerful place to be, where equipment is plentiful and well-maintained, everything works and there are occasional exciting treats such as trips or visitors, and where children whose needs may mean they will work best with specific equipment or an outdoor space etc can have such safe and specific equipment / space provided.
A teacher can be supported by a head who protects them from unreasonable demands from parents, where needed.
A teacher can be supported by well-informed, expert governors who genuinely want to make the school better for all children rather than lobby for their own specific child.
OP, can you see yourself getting involved in any of these ways to support all the teachers in your child's school? Volunteer in another classroom? Perhaps encourage others to volunteer in your child's classroom (and don't pump them for information that they should not give)? Join the PTA to raise money for all children? become a governor who supports the whole school?