A miracle is only another name for something which is yet unexplained, it doesn't mean it has a supernatural cause.
Nope. From the Oxford English Dictionary
noun
1An extraordinary and welcome event that is not explicable by natural or scientific laws and is therefore attributed to a divine agency.
‘the miracle of rising from the grave’
1.1 A remarkable event or development that brings very welcome consequences.
‘it was a miracle that more people hadn't been killed’
‘industries at the heart of the economic miracle’
1.2 An exceptional product or achievement, or an outstanding example of something.
‘a machine which was a miracle of design’
as modifier ‘a miracle drug’