Trace 9 PNG line drawings into animation-ready SVG (centreline)

I have nine simple black line illustrations as PNG files. I need each converted to SVG.

Please use centreline tracing in Inkscape (Path → Trace Bitmap → Centreline tracing). Do not use normal or outline tracing.

Each finished file must have:

Fill set to none, stroke set to black
The same stroke width across all nine files
A viewBox, no fixed width or height
Tight crop, no white space around the artwork
Stray specks removed, broken lines joined where lines cross

These will be animated on a website so the lines draw themselves on screen. Filled shapes won't work, which is why centreline is essential.

Please send one file first so I can check it before you do the rest.