Mount an existing partition without formatting

I’ve installed Arch Linux on /dev/sda2 and it is marked as boot.
But I have all my old files and documents in /dev/sda1 that is not accessible.

When I run sudo mount /dev/sda1 /mnt, there is an error:

mount: /mnt: wrong fs type, bad option, bad superblock on /dev/sda1, missing codepage or helper program, or other error.

How to recover all my old files?

Output of fdisk -l:

Disk /dev/sda: 298.09 GiB, 320072933376 bytes, 625142448 sectors
Disk model: HGST HTS545032A7
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: dos
Disk identifier: 0xe324f148

Device     Boot     Start       End   Sectors   Size Id Type
/dev/sda1            2048 534985522 534983475 255.1G 83 Linux
/dev/sda2  *    541278208 625142447  83864240    40G 83 Linux
/dev/sda3       534986752 541278207   6291456     3G 83 Linux

Partition table entries are not in disk order.

/dev/sda3 is a swap

Output of lsblk /dev/sda1:

NAME MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda1   8:1    0 255.1G  0 part 

Output of file -s /dev/sda1

/dev/sda1: Linux rev 1.0 ext4 filesystem data, UUID=c5c99a23-3374-4e5f-acf0-8ecd014e26cd (extents) (64bit) (large files) (huge files)

Output of e2fsck -f -n /dev/sda1

e2fsck 1.45.6 (20-Mar-2020)
The filesystem size (according to the superblock) is 78142464 blocks
The physical size of the device is 66872934 blocks
Either the superblock or the partition table is likely to be corrupt!
Abort? no

Pass 1: Checking inodes, blocks, and sizes
Inode 789314 extent tree (at level 2) could be narrower.  Optimize? no

Inode 813861 extent tree (at level 1) could be narrower.  Optimize? no

Inode 1322338 extent tree (at level 1) could be shorter.  Optimize? no

Error reading block 67108896 (Invalid argument) while getting next inode from scan.  Ignore error? no

Error while scanning inodes (16654338): Can't read next inode
e2fsck: aborted