It felt like double linked list to me.
It's a single linked list. Each block points to the previous one. It's not possible to blocks to point the next one on the chain, cause 1)it doesn't yet exist 2)there will be possible multiple blocks in the future, every one except one will get orphaned.
The term 'blockchain' is somehow misleading, it's more like a tree data structure. Only most branches diverging from the principal one are ignored after some time, and called 'orphans'.