Hi @YongMoon_Lee, welcome to the community 
n8n would not change the order of items as they are processed sequentially. So the first item before the HTTP request would correspond to the first item after the HTTP request (same for the second, third, etc. item).
Here’s a quick test workflow, you can set any number in the initial Function node if you’d like to double-check this yourself. It uses the /anything endpoint from httpbin.org, which is a great service for testing such scenarios (as it responds simply with the data it has received).