Yes, it is. However, the current firmware is not the official OpenWrt and it almost certainly operates very differently since it is highly customized by the vendor.
You are not only missing the lan side network, but also the firewall and DHCP configuration files.
Either something is very wrong with that installation/configuration, or the vendor has done something very very different than normal.
I'd recommend resetting the device to defaults. You may be able to do this with the standard openwrt method:
firstboot -y && reboot
If that works, it will hopefully get the normal networking functioning properly so that you can upgrade to an official modern version of OpenWrt.
If you cannot get it to reset, you may need to ask the vendor how to reset it or how to get the normal networking to function.