Why can't I import package in the same module?

I have some problem with Golang about importing local only package. This is my project structure

home/src/github.com/username/project1
|main.go
|go.mod
├── handlers
│   ├── handlers.go
├── usecases
|   ├─ ...
|...

my go.mod

module project1
go 1.16

my main.go

package main
import (
	"fmt"
	"net/http"
	
	"project1/handlers/handlers"
)
func main() {
	http.HandleFunc("/", handlers.Greet)
	http.ListenAndServe(":8080", nil)
}

my handlers/handlers.go

package handlers
import (
	"net/http"
	"fmt"
)
func Greet(w http.ResponseWriter, r *http.Request) {
	//Do stuff
}

I'm building this outside the GOPATH which is C:\users\...\go and I am using go 1.16.

After reading some sources that said I can just use the module name and path to the package to import the package I use this line to import handlers package to main package.

import "project1/handlers/handlers"

But this returns this error when I tried to run it.

package project1/handlers/handlers is not in GOROOT (C:\...\project1/handlers/handlers)

Then I tried to change some stuff like changing both my module name and import path to this

//module name in go.mod
module github.com/username/project1
//import path in main.go
import "github.com/username/project1/handlers/handlers"

but then it returns error that said I need to get the package first with go get github.com/username/project1/handlers/handlers which when I tried to get it with that command or just simply go mod tidy returns repository not found error because I haven't push/publish this project and I'm not planning to do it.

So, what is the problem/mistake that I made here? do I have to publish my project before I can import my own local package? Did I miss some configuration? Every single help is appreciated.

I put too many path in the import path, it should stop at the directory rather than package. So by changing the import path to

import "project1/handlers"
//rather than
import "project1/handlers/handlers"

fixed the problem. Thanks!