Here’s a list of old versions of most basic programs that I’ve found while resurrecting an old AMD Turion 64 laptop running Windows XP:

Web browser: Pale Moon/New Moon for XP unofficial http://matejhorvat.si/en/unfiled/pmxp/index.htm
Pale Moon language packs: http://addons.palemoon.org/language-packs/
uBlock Origin 1.13.8: https://addons.mozilla.org/en-US/firefox/addon/ublock-origin/versions/?page=2#version-1.13.8
DownThemAll! 2.0.18.1-signed.1-let-fixed: https://addons.mozilla.org/en-US/firefox/addon/downthemall/versions/?page=1#version-2.0.18.1-signed.1-let-fixed
Codec pack/movie player: K-lite codec pack 13.8.4: http://files2.codecguide.com/K-Lite_Codec_Pack_1384_Full.exe
Office suite: LibreOffice 5.3.x: https://filehippo.com/download_libreoffice_32/5.3.4.2.0/
Antivirus: AVG free, current version: https://www.avg.com

Consider replacing Windows XP with a more modern linux distribution like MX Linux.