Beginner Runner and Heart Rate

Hi! I just started running about 2 months ago and have been pushing through since. I have a question regarding heart rate and speedwork. I recognized I was running “easy” miles without even knowing and only realized when I ran my first 5k last week that I actually can run alot faster. The concern was that my heart rate was too high during the 5k (190s-200s). I honestly go into zone 4 at a pace thats not even my fastest. Is it better to just continue slow miles within a zone 3ish (140-155 bpm for me) heart rate OR is it okay to train at paces that raise my heart rate into zone 4/5 (156-175+)? I have noticed though that the average heart rate is sloooooowly creeping down since Ive started running more 😊💪🏻 Thank you in advance! Just a small 5’1 girl concerned about the heart rate jump when I run (even though it doesnt feel hard 🙄)