Clamp DC current measurements with AmazonCommercial 600A AC/DC Clamp Meter
You're not using it correctly.
You can only have a single wire running though the clamp - in all the cases you show here you have 2 wires - even the 1st pics with the adapter plugged in to the outlet powering the clip-on LED lamp has 2 wires inside that single round cable.
If you use it to measure current from your automotive 12V battery you'll probably be fine since you're only likely to clamp the meter over either the positive or the negative wire at any one point in time.