question about what index formula is doing to transpose

I am using this formula but I don't understand what it is doing. =INDEX($A$5:$H$5,ROWS(B$8:B8))

example attached. it seems to be counting rows as I fill down to give the argument for row_number. I am confused b/c my array is just one row. So if that argument is 1, then 2, then 3 and so on for the row number, how is it pulling the values? seems totally backwards b/c it is really pulling column 1 then, 2, then 3.

followup question is are there any alternative ways to do this? it will be to constantly be transposing date from rows to columns for a report. the source data will be changing a lot and will be across multiple sheets.

thx for the help.

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