Arduino for STM32

It's H5 board, not F1.
You probably won't find a compiled USB bootloader for it, you will have to compile one yourself.
analogRead() is really slow on H5/H7 MCUs.

Did you try to use this library ??

Not enough information.

1. are you 100% sure the LED shouldn't be on ??
2. did you set it up to have com port ??
3. do you connected it to correct usb port ??
4. my crystal ball run out of magic juice... which board you're talking about... ??

To program stm32f103c8t6 blue pill via uart you need to set boot0
and you need stm32cubeprogrammer (or some such programming util)
https://www.st.com/en/development-tools/stm32cubeprog.html
^^ this is from ST (you can consider that an official programming tool)

Isn't that exactly what he wrote ...

Wrong subforum - you're asking about STM32 and posted in STM8.

This won't be done automatically by MCU (with one or a few simple commands).
First you need to measure length of pulses or time between them and by comparing them find the gap to get your program synchronized. Then you can count pulses ...

STM32F103 has a USB interface built-in. Those are PA11 and PA12 pins. But it does not have USB bootloader (called DFU by STM) so you cannot flash firmware using USB without software bootloader (like HID bootloader )

It looks like those jumpers (not resistors) are under CH340 and by default are not ...

What are your settings for UART and USB support in Arduino IDE ??

No, it shouldn't. You can reduce RAM usage to a few 100 bytes disabling unnecessary things.

Output after compiling blink sketch for L011F4:

Sketch uses 4556 bytes (27%) of program storage space. Maximum is 16384 bytes.
Global variables use 412 bytes (20%) of dynamic memory, leaving 1636 bytes for ...

Reduce RAM usage (variables).
You can do it by disabling unused peripherals and not needed features.

stm32duino isn't meant to be used on MCUs with low RAM/ROM. It has a lot "bloatware" to make it universal and easy to use.

1. You don't need to use dfu-util. You can upload directly from Arduino IDE.
2. You don't need U(S)ART enabled for USB serial.
3. If your sketch takes control of USB pins USB Serial won't work.