The next-door neighbours were living here before we moved in.
The people next to us were here before we moved in.
ーThe next-door neighbours were living here before we moved in.
「隣に住んでいる人は、私たちが引っ越してくる前からここに住んでいた」
next-door neighbours で「隣人・隣家の人」
to move in で「新居に入る・移り住む」
ーThe people next to us were here before we moved in.
「私たちの隣の人は、私たちが移り住む前からここにいた」
people next to us で「私たちの隣の人」=「隣人」
ご参考まで!