Single swaps of an array
R, 54 bytes



function(n)combn(n,2,function(x){z=1:n
z[x]=rev(x)
z})


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Returns a matrix where each column is a permutation.

combn(n,k) generates all combinations of size k from the list n, or from 1:n if n is a single integer. It also optionally takes a function FUN to be applied to the resultant combinations. So we write a function that performs the swap and returns the swapped list. The results are then all accumulated into an array, which is in this case 2-dimensional and hence a matrix.