Python 3.8 (pre-release), 263 243 229 226 225 187 168 151 150 bytes
-20 bytes by applying some small modifications.
-14 bytes by emanresu A.
-3 bytes by noodle person.
-75 bytes by ASCII-only.
-1 byte by noodle person.
…Okay, what—
def f(b,c=[]): for i in b:c+=[0,1,2][i::2] for i in range(l:=len(c),-1,-1):print(" "*i+" /"[[0,*c][i]]+" \\"[i>0]+" \\"*(i<l)+" /"[[*c,0,0][i+1]])